Nutrient Limitation of Periphyton and Phytoplankton in Cape Cod Coastal Plain Ponds

TitleNutrient Limitation of Periphyton and Phytoplankton in Cape Cod Coastal Plain Ponds
Publication TypeJournal Article
Year of Publication2009
AuthorsKniffin, Maribeth, Neill Christopher, MCHORNEY RICHARD, and Gregory George
JournalNortheastern Naturalist
Pagination395 - 408
Date Published09/2009
KeywordsCape Cod, nutrient limitation, periphyton, phytoplankton, pond

We investigated nutrient limitation of periphyton and phytoplankton in Cape Cod, MA coastal plain freshwater ponds. We assayed periphyton growth response to nitrogen (N) and phosphorus (P) in situ, assessed phytoplankton growth in growth chambers, and measured ratios of dissolved N and P in surface waters to determine if nutrient ratios were accurate predictors of nutrient limitation. In ponds receiving low groundwater nutrient inputs, periphyton responded weakly to addition of N or P alone, but responded strongly to addition of N+P. In these ponds, increases in both N and P were also required to increase phytoplankton growth. In ponds receiving high ground- water nutrient inputs, increased N+P were also required to increase phytoplankton growth. We found no indication that high nutrient inputs shifted pond phytoplankton to P limitation. There was no consistent correlation between dissolved N:P and whether periphyton was limited by either N or P or co-limited by N and P. Strong and wide- spread co-limitation by N and P suggested that greater attention should be given to both N and P when assessing the threat of nutrient enrichment to fresh waters. Effects of increased periphyton and phytoplankton growth on the unique flora of coastal plain ponds are not known, but bear increased attention given large increases of N in ground- water in many locations, the sensitivity of pond algae to nutrient supply, and the status of coastal plain ponds as high conservation priorities.